Open Access Austin Journal of Anatomy Case Presentation A Persistent Metopic Suture: A Case Report Seth Gardner* Department of Natural and Social Sciences, Bowling Abstract Green State University Firelands, USA An adult human skull found in a college osteological collection presented *Corresponding author: Seth Gardner, Department with a persistent metopic suture. The metopic suture or frontal suture is noted of Natural and Social Sciences, Bowling Green State to be between the two frontal bones extending from the nasion to the bregma. University Firelands, Huron, Ohio, USA The metopic suture generally fuses between 1 and 8 years of life. If it remains after that time it is known as metopism. Its presence is a normal variant of the Received: March 08, 2016; Accepted: March 18, 2016; cranial sutures. Its presence may be mistaken for a skull fracture and also may Published: March 22, 2016 be associated with frontal sinus irregularities. Keywords: Metopic suture; Cranial sutures; Frontal bone Introduction the persistence of the metopic suture in approximately 1-12% of skulls. One author, Agarwal [10] reported the finding of 38.17% in The human frontal bones begin to ossify in the mesenchyme via Indian skulls, and Linc [11] observed it in 11% in Czech skulls, and two ossification centers at approximately eight weeks gestation [1]. finally Woo [12] reported the finding in 10% in Mongoloid skulls. The two bones tend to fuse in the midline via the metopic or frontal The data may suggest that metopism is higher in temperate climates suture. The term metopic is from Greek meaning “in the middle of than in warmer climates [13]. the face” [2]. The metopic suture is a dentate-type suture extending Berry and Berry [14] reported a 0%-7% incidence associated from the nasion to the bregma [3]. The fusion of the metopic suture with ethnicity. Metopism has been found by several investigators as normally begins at the nasion proceeding superiorly and terminates being more prevalent in males than females [15,16]. Castillo reported at the anterior fontanelle [4]. The suture is situated almost exactly a world index of incidence of 2.75%. It has also been reported to on the median line of the two frontal bones [2]. It usually will close be perhaps associated with frontal sinus abnormalities but those within the first or second year of life, but it has been reported to take studies seem flawed [2]. Some authors reported various suspected up to seven years to fuse [5]. Racial variations have been reported causes of metopism, including active expression of cytokines during in the literature [6], as well as complications related to incomplete cranial fusion and even resorption of the chondroidal tissue [6]. One development of the frontal sinus. When the metopic suture persists author states “that a persistent metopic suture probably occurred in into adulthood it is known as “metopism”. It is rare to find this suture conjunction while refining the ability to walk” [8]. The author further in adults and its presence is not considered pathological. However, notes that the persistent metopic suture is an adaptation for giving premature closure of any of the cranial sutures results in a pathology birth to babies with larger brains, and is related to the shift to a rapidly known as craniosynostosis [3]. Case Presentation A dry human skull used in the anatomy program at Bowling Green State University Firelands in Huron, Ohio was found to have a persistent metopic suture or metopism. Based upon the size and shape of the piriform aperture as well as the various other anthropometric markings, the skull was suspected to be from a black male of unknown age. The two frontal bones were clearly seen due to the complete metopic suture. The suture extended from the bregma to the nasion as seen in Figure 1. Discussion The persistence of the metopic suture is called metopism. This suture disappears by the second or third year of life. It is thought to be a normal variant of the cranial sutures [7]. It forms from the lack of union of the two frontal bones during embryonic development. Del Sol [8] suggested that metopism can be related to abnormal growth of the cranial bones, hydrocephalus, heredity, or atavism. The genetic factor is the one currently accepted by most scientists [9]. Metopism is found in approximately 5% of Asians and 9% of Figure 1: The White arrow indicates Bregma. The Black arrow indicates European Caucasians and 1% of Blacks [1,7]. Bergman [7] reported Metopic Suture. The Red arrow indicates the Nasion. Austin J Anat - Volume 3 Issue 1 - 2016 Citation: Gardner S. A Persistent Metopic Suture: A Case Report. Austin J Anat. 2016; 3(1): 1049. ISSN : 2381-8921 | www.austinpublishinggroup.com Gardner. © All rights are reserved Seth Gardner Austin Publishing Group growing brain after birth and even may be related to the expansion of 7. Bergman RA, Afifi AK, Miyauchi Ret. “Compendium of human anatomical the frontal lobes [8]. variation: text, atlas and world literature”. Baltimore, Urban and Schwarzenberg. 1988; 41: 282-288. Conclusion 8. Falk D, Zollikoferc CPE, Morimotoc N, de Leónc MSP. “Metopic suture of Taung (Australopithecus africanus) and its implications for hominin brain The presence of a metopic suture is important from a clinical evolution”. Proceedings of the National Academy of Sciences. 2012; 109: point of view. It must be included in the differential diagnosis of a 8467-8470. suspected skull fracture particularly of the frontal bone. It is not a 9. Castillo SMA, Oda YJ, Santana GDM. “Metopism in Adult Skulls from pathological entity but most certainly should be noted as an incidental Southern Brazil”. International Journal of Morphology. 2006; 24: 61-66. finding on an x-ray. The suture is best identified in an A-P view of the 10. Agarwal SK, Malhotra VK, Tewari SP. Incidence of the metopic suture in adult skull. This view can help differentiate it from a vertical skull fracture. Indian crania. Acta Anat (Basel). 1979; 105: 469-474. Neurosurgeons should be aware of the many suture configurations 11. Linc R, Fleischman J. Incidence of Metropism in the Czech Population and its before cranial surgery. causes C.R. Ass. Anat. Comptesrendus Del’ Association des Anatomistes’. 1969; 142: 1192-1202. References 1. Verma P. International Journal of Anatomical Variations. 2014; 7: 7-9. 12. Woo JK. Ossification and growth of the human maxilla, premaxilla and palate bone. Anat Rec. 1949; 105: 737-761. 2. Guerram A, Le Minor JM, Renger S, Bierry G. “Brief communication: The size of the human frontal sinuses in adults presenting complete persistence 13. Anjoo Yadav, Vinod Kumar, Srivastava RK. “Study of Metopic Suture in the of the metopic suture”. American Journal Of Physical Anthropology. 2014; Adult Human Skulls of North India”. Journal of the Anatomical Society of 154: 621-627. India. 2010; 59: 144-244. 3. Bilgin S, Kantarcı UH, Duymus M, Yildirim CH, Ercakmak B, Orman G, et 14. Carolineberry A, Berry RJ. Epigenetic variation in the human cranium. J Anat. al. Association between frontal sinus development and persistent metopic 1967; 101: 361-379. suture. Folia Morphol (Warsz). 2013; 72: 306-310. 15. Murlimanju BV, Prabhu LV, Pai MM, Goveas AA, Dhananjaya KV, Somesh 4. Chaoui R, Levaillant JM, Benoit B, Faro C, Wegrzyn P, Nicolaides KH. MS. “Median frontal sutures-incidence, morphology and their surgical, “Three-dimensional sonographic description of the fetal frontal bones and radiological importance,” Turkish Neurosurgery. 2011; 21: 489-493. metopic suture”. Ultrasound in obstetrics & gynecology. 2005; 26: 618-621. 16. Baaten PJ, Haddad M, Abi-Nader K, Abi-Ghosn A, Al-Kutoubi A, Jurjus AR. 5. Baaten PJ, Haddad M, Abi-Nader K, Abi-Ghosn A, Al-Kutoubi A, Jurjus AR. Incidence of metopism in the Lebanese population. Clin Anat. 2003; 16: 148- Incidence of metopism in the Lebanese population. Clin Anat. 2003; 16: 148- 151. 151. 6. Vikram S, Padubidri JR, Dutt AR. “A rare case of persistent metopic suture in an elderly individual: Incidental autopsy finding with clinical implications”. Archives of Medicine and Health Sciences. 2016; 2: 61. Austin J Anat - Volume 3 Issue 1 - 2016 Citation: Gardner S. A Persistent Metopic Suture: A Case Report. Austin J Anat. 2016; 3(1): 1049. ISSN : 2381-8921 | www.austinpublishinggroup.com Gardner. © All rights are reserved Submit your Manuscript | www.austinpublishinggroup.com Austin J Anat 3(1): id1049 (2016) - Page - 02.